From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Linux PM <linux-pm@vger.kernel.org>,
Stephen Boyd <sboyd@kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
Kevin Hilman <khilman@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Lina Iyer <ilina@codeaurora.org>,
Tony Lindgren <tony@atomide.com>,
Sudeep Holla <sudeep.holla@arm.com>,
"Raju P . L . S . S . S . N" <rplsssn@codeaurora.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v10 00/27] PM / Domains: Support hierarchical CPU arrangement (PSCI/ARM)
Date: Fri, 11 Jan 2019 12:08:32 +0100 [thread overview]
Message-ID: <2260944.bWjCqvLuxn@aspire.rjw.lan> (raw)
In-Reply-To: <CAPDyKFpV0uQhZnJhSg79RxmCq+0PFUeaXCgmBgRU5aNF8WNoDw@mail.gmail.com>
On Monday, December 17, 2018 5:12:54 PM CET Ulf Hansson wrote:
> Rafael, Sudeep, Lorenzo, Mark,
>
> On Thu, 29 Nov 2018 at 18:47, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> >
> > Over the years this series have been iterated and discussed at various Linux
> > conferences and LKML. In this new v10, a quite significant amount of changes
> > have been made to address comments from v8 and v9. A summary is available
> > below, although let's start with a brand new clarification of the motivation
> > behind this series.
> >
> > For ARM64/ARM based platforms CPUs are often arranged in a hierarchical manner.
> > From a CPU idle state perspective, this means some states may be shared among a
> > group of CPUs (aka CPU cluster).
> >
> > To deal with idle management of a group of CPUs, sometimes the kernel needs to
> > be involved to manage the last-man standing algorithm, simply because it can't
> > rely solely on power management FWs to deal with this. Depending on the
> > platform, of course.
> >
> > There are a couple of typical scenarios for when the kernel needs to be in
> > control, dealing with synchronization of when the last CPU in a cluster is about
> > to enter a deep idle state.
> >
> > 1)
> > The kernel needs to carry out so called last-man activities before the
> > CPU cluster can enter a deep idle state. This may for example involve to
> > configure external logics for wakeups, as the GIC may no longer be functional
> > once a deep cluster idle state have been entered. Likewise, these operations
> > may need to be restored, when the first CPU wakes up.
> >
> > 2)
> > Other more generic I/O devices, such as an MMC controller for example, may be a
> > part of the same power domain as the CPU cluster, due to a shared power-rail.
> > For these scenarios, when the MMC controller is in use dealing with an MMC
> > request, a deeper idle state of the CPU cluster may needs to be temporarily
> > disabled. This is needed to retain the MMC controller in a functional state,
> > else it may loose its register-context in the middle of serving a request.
> >
> > In this series, we are extending the generic PM domain (aka genpd) to be used
> > for also CPU devices. Hence the goal is to re-use much of its current code to
> > help us manage the last-man standing synchronization. Moreover, as we already
> > use genpd to model power domains for generic I/O devices, both 1) and 2) can be
> > address with its help.
> >
> > Moreover, to address these problems for ARM64 DT based platforms, we are
> > deploying support for genpd and runtime PM to the PSCI FW driver - and finally
> > we make some updates to two ARM64 DTBs, as to deploy the new PSCI CPU topology
> > layout.
> >
> > The series has been tested on the QCOM 410c dragonboard and the Hisilicon Hikey
> > board. You may also find the code at:
> >
> > git.linaro.org/people/ulf.hansson/linux-pm.git next
>
> It's soon been three weeks since I posted this and I would really
> appreciate some feedback.
>
> Rafael, I need your feedback on patch 1->4.
Sorry for the delay, I've replied to the patches.
The bottom line is that the mechanism introduced in patch 3 and used
in patch 4 doesn't look particularly clean to me.
Cheers,
Rafael
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next prev parent reply other threads:[~2019-01-11 11:09 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-29 17:46 [PATCH v10 00/27] PM / Domains: Support hierarchical CPU arrangement (PSCI/ARM) Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 01/27] PM / Domains: Add generic data pointer to genpd_power_state struct Ulf Hansson
2018-12-18 10:39 ` Daniel Lezcano
2018-12-18 11:53 ` Ulf Hansson
2019-01-11 10:52 ` Rafael J. Wysocki
2018-11-29 17:46 ` [PATCH v10 02/27] PM / Domains: Add support for CPU devices to genpd Ulf Hansson
2018-12-19 9:53 ` Daniel Lezcano
2018-12-19 10:02 ` Ulf Hansson
2019-01-11 10:54 ` Rafael J. Wysocki
2018-11-29 17:46 ` [PATCH v10 03/27] timer: Export next wakeup time of a CPU Ulf Hansson
2019-01-11 11:06 ` Rafael J. Wysocki
2019-01-16 7:57 ` Ulf Hansson
2019-01-16 10:59 ` Rafael J. Wysocki
2019-01-16 12:00 ` Ulf Hansson
2019-01-25 10:04 ` Ulf Hansson
2019-01-25 10:18 ` Rafael J. Wysocki
2018-11-29 17:46 ` [PATCH v10 04/27] PM / Domains: Add genpd governor for CPUs Ulf Hansson
2018-12-19 9:54 ` Daniel Lezcano
2018-12-19 10:09 ` Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 05/27] dt: psci: Update DT bindings to support hierarchical PSCI states Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 06/27] of: base: Add of_get_cpu_state_node() to get idle states for a CPU node Ulf Hansson
2018-12-19 11:05 ` Daniel Lezcano
2018-11-29 17:46 ` [PATCH v10 07/27] cpuidle: dt: Support hierarchical CPU idle states Ulf Hansson
2018-12-19 11:20 ` Daniel Lezcano
2018-11-29 17:46 ` [PATCH v10 08/27] ARM/ARM64: cpuidle: Let back-end init ops take the driver as input Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 09/27] drivers: firmware: psci: Move psci to separate directory Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 10/27] MAINTAINERS: Update files for PSCI Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 11/27] drivers: firmware: psci: Split psci_dt_cpu_init_idle() Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 12/27] drivers: firmware: psci: Simplify state node parsing Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 13/27] drivers: firmware: psci: Support hierarchical CPU idle states Ulf Hansson
2018-12-19 12:11 ` Daniel Lezcano
2018-12-19 12:53 ` Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 14/27] drivers: firmware: psci: Simplify error path of psci_dt_init() Ulf Hansson
2018-12-19 12:08 ` Daniel Lezcano
2018-11-29 17:46 ` [PATCH v10 15/27] drivers: firmware: psci: Announce support for OS initiated suspend mode Ulf Hansson
2018-12-20 13:11 ` Daniel Lezcano
2018-11-29 17:46 ` [PATCH v10 16/27] drivers: firmware: psci: Prepare to use " Ulf Hansson
2018-12-20 14:08 ` Daniel Lezcano
2018-12-20 15:41 ` Ulf Hansson
2018-12-20 17:16 ` Daniel Lezcano
2018-11-29 17:46 ` [PATCH v10 17/27] drivers: firmware: psci: Prepare to support PM domains Ulf Hansson
2018-12-20 14:19 ` Daniel Lezcano
2018-12-20 15:49 ` Ulf Hansson
2018-12-20 18:06 ` Daniel Lezcano
2018-12-20 21:37 ` Ulf Hansson
2018-12-21 7:15 ` Daniel Lezcano
2018-11-29 17:46 ` [PATCH v10 18/27] drivers: firmware: psci: Add support for PM domains using genpd Ulf Hansson
2018-12-03 16:37 ` Lina Iyer
2018-12-03 20:03 ` Ulf Hansson
2018-12-20 14:35 ` Daniel Lezcano
2018-12-20 21:09 ` Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 19/27] drivers: firmware: psci: Add hierarchical domain idle states converter Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 20/27] drivers: firmware: psci: Introduce psci_dt_topology_init() Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 21/27] drivers: firmware: psci: Add a helper to attach a CPU to its PM domain Ulf Hansson
2018-12-04 18:45 ` Lina Iyer
2018-12-06 9:15 ` Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 22/27] drivers: firmware: psci: Attach the CPU's device " Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 23/27] drivers: firmware: psci: Manage runtime PM in the idle path for CPUs Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 24/27] drivers: firmware: psci: Support CPU hotplug for the hierarchical model Ulf Hansson
2018-11-29 22:31 ` Lina Iyer
2018-11-30 8:25 ` Ulf Hansson
2018-11-30 20:57 ` Lina Iyer
2018-12-19 11:17 ` Lorenzo Pieralisi
2018-12-19 11:47 ` Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 25/27] arm64: kernel: Respect the hierarchical CPU topology in DT for PSCI Ulf Hansson
2018-11-29 17:46 ` [PATCH v10 26/27] arm64: dts: Convert to the hierarchical CPU topology layout for MSM8916 Ulf Hansson
2018-11-29 17:47 ` [PATCH v10 27/27] arm64: dts: hikey: Convert to the hierarchical CPU topology layout Ulf Hansson
2018-12-17 16:12 ` [PATCH v10 00/27] PM / Domains: Support hierarchical CPU arrangement (PSCI/ARM) Ulf Hansson
2019-01-11 11:08 ` Rafael J. Wysocki [this message]
2019-01-03 12:06 ` Sudeep Holla
2019-01-16 9:10 ` Ulf Hansson
2019-01-17 17:44 ` Sudeep Holla
2019-01-18 11:56 ` Ulf Hansson
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